How the hours between two times are calculated
The calculator converts each time to minutes since midnight, subtracts the start from the end, adds 24 hours if the result is negative (an overnight shift), then removes the unpaid break. The remainder is shown three ways: as hours and minutes, as decimal hours to two places, and as raw minutes. When you also give a start and end date, it works from the two full date-times instead, so a span like Friday 10 pm to Monday 6 am comes out as 2 days 8 hours rather than a single overnight guess.
Worked examples
| Start | End | Break | h:mm | Decimal |
|---|---|---|---|---|
| 9:00 am | 5:30 pm | 30 min | 8:00 | 8.00 |
| 8:15 am | 4:50 pm | 30 min | 8:05 | 8.08 |
| 7:00 am | 3:00 pm | 0 | 8:00 | 8.00 |
| 10:00 pm | 6:00 am | 0 | 8:00 | 8.00 |
| 6:45 am | 7:20 pm | 45 min | 11:50 | 11.83 |
| 1:30 pm | 1:15 pm (next day) | 60 min | 22:45 | 22.75 |
Doing it by hand
Write both times as hours and minutes on a 24-hour clock. Subtract the minutes first; if the end minutes are smaller, borrow 60 from the hours. Then subtract the hours. For 8:15 to 16:50: 50 minus 15 is 35 minutes, 16 minus 8 is 8 hours, so 8 hours 35 minutes. Take off a 30-minute break to get 8 hours 5 minutes. To convert to decimal, divide the leftover minutes by 60: 5 / 60 = 0.083, so 8.08 hours. If you need this for a full week, the time card calculator does the same sum for seven days and applies overtime.
Why the decimal matters
Invoices and payroll multiply hours by a rate. If you bill 8 hours 5 minutes as "8.05" you have quietly given away 3 minutes; over a year of daily errors like that the gap is measured in hours. The correct figure is 8.08 (or 8.083 if your system takes three places). The conversion chart lists every minute from 1 to 60.
Overnight and multi-day spans
Without dates, an end time earlier than the start time is assumed to be the next morning, which covers almost every night shift. With dates, there is no assumption: the calculator uses the exact interval, reports whole days separately, and still shows the total in hours so you can drop it straight into a timesheet. Daylight-saving transitions are ignored; the tool counts clock hours, which is what nearly every employer pays on.